Fast MR Image Registration for MRI-guided Intervention
Magnetic Resonance Imaging (MRI) offers high resolution images to visualize soft tissue details, allowing clinicians to identify critical regions such as tumors margins and neurovascular and muscular structures. To visualize physiological changes of soft tissues during surgical intervention, fast image registration techniques are necessary to align pre-operative and intra-operative images. We are developing navigation systems that enable intra-operative MRI-guided interventions. The main components are i) fast image registration using advanced computing units (e.g. graphical computing units (GPUs), field-programmable gate arrays (FPGAs)), so as to achieve high-quality intra-operative MRI; ii) miniaturized MR tracking units for accurate and rapid positional sensing of surgical tools, which close the loop of the intervention; and iii) human-robot control interface that provide allows intuitive manipulation of robotic surgical tools. These components are particularly beneficial to minimal invasive surgeries (MIS) such as cardiac electrophysiology, deep brain stimulation, transoral surgery, etc., providing safe, precise and effective control of surgical instruments.
Wireless Multilayer Tracking Marker for MRI-guided Intervention
[Video: MRI-based real-time instrument tracking using two wireless markers]
Magnetic Resonance (MR) compatible wireless markers can provide 3D positional tracking under MR imaging, which would facilitate MRI-guided navigation of interventional tools, in particular for those assisted by tele-operated robots. However, a major hurdle is the integration of wireless markers with surgical instruments, which requires small size but still sufficient quality factor. To this end, we propose a new design and fabrication approach of a tiny and thin wireless MR-tracking marker (6.7 mm × 1.5 mm × 0.3 mm), much smaller than those seen in prior art, but with a quality factor (Q factor 28.5) still comparable to them. This design and fabrication approach are reportedly the first design to initiate wireless markers in such a small size, enabling straightforward integration with interventional tools. When validated under MRI, the tracking marker appeared as a very high contrast spot on the MR images. For a 48 mm distance from the isocenter, the estimated maximum errors in 3D position was 0.48 mm. And the inherent standard deviation of marker localization was 0.12 mm. With the high MR contrast signal generated, the presented markers enable automatic and real-time tracking in 3D, but without MR image construction.
 C.L. Cheung, K.H. Lee, Z. Guo, Z. Dong, C.W. Leong, Y. Chen, P.W. Lee, K.W. Kwok, "Kinematic-model-free Positional Control for Robot-assisted Cardiac Catheterization", in the Proceedings of the Hamlyn Symposium on Medical Robotics, pp.80-81, 2016. Detail
 Y. Chen, W. Wang, E. J. Schmidt, K.W. Kwok, A. N. Viswanathan, R. Cormack, and Z. T. H. Tse, "Design and Fabrication of MR-Tracked Metallic Stylet for Gynecologic Brachytherapy," IEEE/ASME Transactions on Mechatronics, vol. 21, no. 2, pp.956-962, 2016. Detail
 K.W. Kwok, K.H. Lee, Y. Chen, W. Wang, Y. Hu, G.C.T. Chow, S.H. Zhang, W.G. Stevenson, R.Y. Kwong, W. Luk, E.J. Schmidt, Z.T.H. Tse, "Interfacing Fast Multi-phase Cardiac Image Registration with Real-time MRI-based Catheter Tracking for MRI-guided Electrophysiological Ablative Procedures," Circulation, 130(Suppl 2):A18568, 2014. Detail
1. Merit Poster Award in the IEEE International Conference on Robotics and Automation (ICRA) 2017, presented by the workshop C4 Surgical Robots: Compliant, Continuum, Cognitive, and Collaborative.
Authors and title: Z. Dong, Z. Guo, K.C.D. Fu, K.H. Lee, M.C.W. Leong, C.L. Cheung, A.P.W. Lee, W. Luk and K.W. Kwok, "A Robotic Catheter System for MRI-guided Cardiac Electrophysiological Intervention."
2. Best Live Demonstration prize – Surgical Robot Challenge 2016, organized by EPSRC UK-RAS Network.
Title: "MR-conditional Catheter Robot for MRI-guided Cardiac Electrophysiological Intervention."
1. PCT Provisional Pat: Robotic Catheter System for MRI-guided Cardiovascular Interventions: PCT/CN2017/089701 (Filed on 2017. Licensed by APTUS Therapeutics Limited.)
2. US Provisional Pat: Robotic Catheter System for MRI-guided Cardiovascular Interventions: US 15/630,406 (Filed on Jun 24, 2016. Licensed by APTUS Therapeutics Limited.)